Geometrical and drafting instrument.



C. A. GILSON.

G0METRICAL AND DRAFTING INSTRUMENT.

AP'PL'icmoN FILED MAY 4'. 191a.

Patented J an. 14, 1919.

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CLAIR A. GILSON. 0F NILES, MICHIGAN.

GEOMETRICAL AND DRAFTING INSTRUMENT.

Specification of Letters Patent.

Patented Jan. 14., 1919'.

Application filed May 4. 1916. Serial No. 95,369.

To all whom it may concern:

Be it known that I, CLA-In A. GILSON, a citizen of the United States, and resident of Niles, in the county of Berrien and State of Michigan, have invented certain new and useful Improvements in Geometrical and Drafting Instruments, of which the following is a specification.

The present invention relates to new and useful improvements in drafting instruments and more particularly to an improved triangle and protractor.

The primary object of my invention is to provide a combination protractor, integrator, and 30-60 triangle.

My invention contemplates the provision of an improved drafting instrument combining a number of instruments in one and with this end in view I provide a drafting triangle having symmetrical curves associated therewith, irregular curves associated therewith, and angle protracting indicia thereon.

With the above and other objects in view my invention consists in the structure hereinafter described and claimed, the same being shown in the accompanying drawing, in which Figure 1 represents a plan view of a draft ing instrument embodying the improvements of my invention.

Fig. 2 is a diagrammatic view of the application of my drafting instrument for determining areas.

Referring more particularly to the drawing, wherein similar characters of reference designate like and corresponding parts, 1 designates the body of my improved drafting instrument, said body being of a configuration conforming to the shape of the usual 45 triangle. Along the two shorter sides 2 and 3 of the triangle I provide indicia 4 and 5 indicating in degrees for protracting purposes, said indicia radiating from a point 6 at the base or lower edge 7 of the triangle. It will be readily apparent that the edge 7 is the hypotenuse of the triangular body 1 and when using the device of my invention in its usual capacity said edge Wlll be the base edge. Therefore, I will hereinafter term the edge 7 as the base edge of the triangle.

Extending upwardly from the point 6 to the vertex of the triangle I provide a line device one 8 dividing the body 1 into two right-angle triangles 9 and 10, said line bein at 90 relative to a straight edge of the body. The triangles 9 and 10 are provided with openings 11 and 12 of various shapes,tl1e ad acent marginal edges of said openings being in the form of symmetrical curves 13 and 14, respectively. The symmetrical curves 13 and 14 are the major curves of the portion of each curve being adjacent the base edge of the triangle 1, the other portions of the curves being arranged on either side of the line 8 and equi-distant therefrom. A plurality of irregular curves 15, 16 and 17 may be provided for obvious purposes. The outer marginal edges of the openings 11 and 12 are straight edges and are designated 18 and 19, the edges 18 being at an angle of 60 with the base edge 7 and the edge 19 being at a 30 angle with the said base edge. This arrangement provides a 75 angle between the edge 18 and the edge 3 of the same triangle and a 15 angle between the edge 19 and the last mentioned edge 3. Thus it will be seen that a plurality of various angular relations may be obtained, the major ones being 30-60, 15-? 5 and a 45 triangle. In this manner I provide three angular combinations which would ordinarily necessitate the provision of a number of different triangles.

I An intermediate curve 20 is provided, said curve 20 being located adjacent the curve 14 hereinbefore referred to, said curve 20 being about the same length as said curve 14. The curve 20 performs the function which will hereinafter appear.

The curves 13 and 14 are so relatively positioned that the shortest distance between these curves at any point multiplied by the height of this point from the base line, is always equal to one square inch. The curves 20 and 14 are so relatively positioned that the shortest distance between these curves to any point multiplied by the height of this point from the base line is always equal to one-tenth of one square inch.

To find thearea of the figure D, N, H, K, indicated in the Fig. 2 of the drawings, draw the vertical lines AC and BK and any horizontal line AB. Place the instrument as shown by the dotted line, with the curve 13 of the instrument tangent to the figure at point C marking the point D. Then slide the instrument on the line AB until the curve 13 comes to D; keeping the instrir ment to the right of the base. The curve 14 will then give the pointE. Move the in strument across the figure, marking the points F, G, H and I, as each space issubtended. To locate the points J and K, the intermediate curve 20 that indicates an area of one tenth of a square inch can be used. The area of the part of the figure which is below the portion of the curve CD. is one square inch, as previously stated, the width CD multiplied by the height frbm the base line is always equal to one square inch. The instrument being moved six times in going from G to I, and twice from I to K, thus gives the area of KG as 6.2 square inches. In a similar manner, A, N, M, B, is 2.1 square inches, and the area ofthe' figure is 6.22.1 which equals 4.1 square inches.

It will thus be seen that in the provision of inyimproved drafting instrument I have afi'orded an instrument which embodies in a single device a structure permitting the use of the device. in as many as six diflerent capacities, namely, a 30-60 triangle, a 15-7 5 triangle, an irregular curve, a curve radiator, a triangle, and an areadeterminer, the last mentioned being for the purpose of determining areas of plane figures.

From the above description taken in connection with the accompanying drawings, it is thought that a clear and c-omprehensive understanding ous uses to which my improvedv drafting instrument may be put will be readily apparent a ldI reserve the right to make such changes in the relative proportion of the device as do not depart from the spirit and scope of the invention as claimed.

Having thus fully described my invention,

copies or scribed including a triangular of the construction and] vari-.

this patent may be obtained for ave cents each, by addressing the what I claim as new and desire to secure by Letters Patent, is:

1. A drafting instrument of the class debody having a dividing line extending from vertex thereof to the opposite base edge, said triangle being provided. on opposite sides of said dividing line with openings, the marginal edges of said openings adjacent the base and said dividing line being in the form of symmetrical curves, and said curves being of such shape that the length of the shortest line between any point on one curve and the base multiplied by the length of the line drawn from such point parallel to the base to the other curve is equal to a given area.

2. A. drafting instrument of the class described including a triangular body having a dividing line extending fronrthe vertex thereof to the opposite base edge, said triangle being provided on opposite sides of said dividing line with openings, the marginal edges of said openings adjacentthe base and said dividing line being in the form of symmetrical curves, said curves beingof such shape that the length of the shortest line between any point on one curve and the base multiplied by the length of the line drawn from such point parallel to base to the other curve is equal to a given area, and an additional symmetrical curve s0 relatively positioned to one of the first mentioned curves that the length of theshortest line between any point on one curve and the base multiplied by the length of the line drawn from such point parallel to the base to the other curve is equal to a prede termined fraction of the given area.

In testimony whereof, I afiix my signature hereto.

CLAIR A. GILS ON.

"commissioner of Pateeia Washington, D. 0. 

